1. Field of the Invention
The present invention relates generally to retractable coverings for architectural openings such as windows, doors, archways and the like and more particularly to an operating system for such a covering.
2. Description of the Relevant Art
Retractable coverings for architectural openings such as windows, doors, archways and the like are well-known in the art and have been in use for many years. Examples of such coverings include curtains, Venetian blinds, vertical blinds, cellular shades and the like. Such retractable coverings typically are movable with an operating system between a retracted position adjacent one or two sides of the architectural opening and an extended position across the architectural opening.
Numerous systems have been employed for reversibly moving coverings between extended and retracted positions. One such system employs a base rail to which an edge of a fabric material is secured, and to which a finger slide is adapted to move linearly. The finger slide anchors one end of two separate operating cords. The opposite ends of the operating cords are anchored to a movable plate positioned adjacent to an opposite edge of the fabric material. The guide cords in combination effectively form an endless loop of cord with the endless loop also slidably passing through a cord reverse bracket anchored to the frame around the architectural opening. In a conventional manner, movement of the finger slide along the base rail in one direction or the other causes the effective endless loop of cord to move in one direction or another, thereby moving the anchor plate and the edge of the fabric between extended and retracted positions of the covering.
As will be appreciated, it is desirable in such systems to retain a predetermined tension in the operating cords as too much slack or too much tension renders the system difficult to operate. In order to adjust the tension in the operating cords, the prior art has provided for adjustment to the location at which the ends of the operating cords are secured to the anchor plate, but if the anchor plate is concealed within the fabric of the covering, such adjustment is difficult to make. Further, routing of the operating cords through the base rail requires reversing directions of the operating cords through sharp angles, and it is thereby difficult to obtain a reliable smooth movement of the operating cords through the base rail. Such operating systems are useful, however, particularly with coverings of nonrectangular configuration such as those having an arched upper edge that is adapted to conform to an arched frame around the architectural opening.
It is to overcome the shortcomings in the prior art and to provide a new and improved operating system for retractable coverings that the present invention has been developed.